1. Field of the Invention
This invention relates to a radio communication device and a radio communication method.
2. Description of the Related Art
In conventional communication systems of a time division multiple access (TDMA) type, such as a portable phone, a network structure is generally used in which a base station is disposed in every predetermined area and a terminal unit is provided under the base station.
In this case, an access method is used in which the base station controls a transmission frame and a slot so that a channel by which each terminal unit can perform transmission or reception is strictly specified.
In a slot division type channel reservation communication system, a network structure is generally used in which a device of an access point is disposed in the center of the network and the terminal unit is provided thereunder.
In this case, also, an access method is used in which the access point consolidates the transmission frame and the slot so that the channel by which each terminal unit can perform transmission or reception is specified strictly.
As an example of such a conventional channel reservation control method, an access method is generally used in which, by means of a channel called a random access slot, the terminal unit sends a reservation request for a channel required for communication to the base station or the access point, so that the terminal unit may carry out communication in the channel specified by the base station or the access point.
On the other hand, as a radio network structure under the IEEE 802.11 standard, a method in which all terminal units perform access control asynchronously without providing a specific base station has been suggested.
As a radio access control method in the radio network under the IEEE 802.11 standard, a collision avoidance method by a carrier sense multiplex access (CSMA/CA) is widely known.